Let’s talk about empathy. The character most associated with empathy is obviously Will Graham, and this empathy is one of his most attractive qualities to various characters for a variety of reasons. Alana and Chilton have a professional curiosity about him, Jack views it as a useful tool in stopping the most violent criminals he faces, and it is one of the main reasons Hannibal falls in love with him because it allows him to be seen and understood in ways no one else has before. In some ways, Hannibal actually loves Will for one of the qualities that set them apart.
The few times he does it, Will kills to exact righteous vengeance on men who deserve it. He kills Hobbs with ten gunshots but quickly enough that he dies on the spot. Randall too is punched immediately to death. He helps Hannibal kill Dolarhyde through massive blood loss by gutting him. His aim is death, not suffering. He isn’t interested in ritualistic murder like Dolarhyde or prolonged suffering like some of the other murderers on the show (think of the Muralist or Eldon Stammets whose victims live for a long time despite mutilation).
On the other hand, Hannibal is diametrically opposed to Will when it comes to empathy. If Will is an empath, then Hannibal is a sadist. Hannibal, despite all his talk of being an ethical butcher, removes organs from his victims while they’re still living. He is a sadist, he enjoys manipulating others and worsening their suffering for his own enjoyment. People aren’t people to him - they’re pigs and he treats them as such, subhuman pawns to do with as he likes. He can play with them and he can make art with them and he can eat them.
But Hannibal is keenly interested in Will’s empathy, and is interested in engaging with it, even if it is on a superficial level. In 2x01 Kaiseki, with Will incarcerated in the BSHCI, Hannibal gets called to help the FBI as a consultant. Hannibal, who never ever considers the thought processes or viewpoints of others outside how they can impact his plans and designs, willingly and almost giddily tries to inhabit Will. Of course, this serves a dual purpose as he also ingratiates himself within the FBI and becomes even more of an ally to Jack, but there is a part of him that loves it. There’s something euphoric in being the only man to empathise with the man who empathises with others, something beautiful about understanding the only man who understands you.
Now let’s talk about pain. We see Will in pain a lot and he expresses that as the most of us would - he sounds like the physical hurt is an anguish. His distress is evident, he feels and he feels acutely. Conversely, Hannibal doesn’t react to getting crucified other than concern over being strangled, barely reacts to being burned on the back and branded like a pig, and looks shocked as he is shot, only breathing a little heavily afterwards. But look at his face when Will gets stabbed by Francis Dolarhyde.
This right here, this snarl of pain, it’s not for him. It’s for Will. For the first time in his life, Hannibal truly empathises with someone else. It’s not even a conscious choice like in Kaiseki nor does it serve any other purpose; it’s completely involuntary. He feels Will’s pain right here - it’s not superficial, it’s instinctual. And while he had been unwilling to fight against the Dragon for his own sake, this moment of pain motivates him enough to get up off the ground and get him off of Will, even though he is grievously injured.
Think about that for a second. A man defined by his own self proclaimed inability to see other human beings as people, who treats the suffering of others as something to be studied clinically and exploited for his own purposes, is empathising with the love of his life because after everything, he cannot stand to see him in pain.
It’s not a redemption arc - Hannibal is beyond redemption and even if he wasn’t, he’s not looking to be redeemed. He likes who he is. But it is about the humanising power of love, specifically how love can take a man like Hannibal Lecter and make him experience the same human emotions that everybody else does. Make him smile when Will does, make him feel nourishment at the very sight of him, make him wince when Will is stabbed. Love can make monsters of us all, but it can make a human out of Hannibal Lecter.